Microbial pathogens in moderate to severe diabetic foot infections

Foot infections are the most common complications in diabetic patients and common cause of morbidity and mortality. They require prompt diagnosis and involvement of a multidisciplinary team in their treatment. Prospective study to define the etiology of the deep diabetic foot infections and its specific characteristics concerning the adequate empiric antimicrobial therapy was done. The study included 50 patients, who underwent minor amputations due to moderate to severe infection of the foot. All specimens for microbiology testing were taken by biopsy or aspiration during surgery. Specimens cultivation, identification of the isolated microorganisms and their susceptibility towards antimicrobial agents were performed by conventional methods and automated systems. Diabetic foot infections were predominantly polymicrobial; 42 (84%) of the cases, caused by associations between two, three and four different pathogens. Mixed infections caused by aerobic and anaerobic bacteria were found in 17 patients (34%). Gram-positive bacteria were the prominent microbial pathogens in both monobacterial and polymicrobial infection; mostly Streptococcus agalactiae and Staphylococcus aureus. Gram-negative aerobic bacteria presented 33.3% of all isolated bacteria, predominantly members of Enterobacteriaceae family. Obligate anaerobes represents 16.66% of all isolated bacteria and were causative organisms in 17 (34%) of the patients, more than the other Bacteroides fragilis group and anaerobic streptococci. The strains isolated were susceptible to the recommended antibacterial agents for treatment of moderate and severe diabetic foot infections (DFIs). The optimal approach to DFIs requires immediate surgical intervention, revascularization in the setting of a multisegment vascular lesions, microbiological examination of suitable clinical materials and appropriate antibacterial therapy for empiric treatment of aerobic and anaerobic pathogens